1. Field of the Invention
The present invention relates to an apparatus for folding an air bag body.
2. Description of the Related Art
Conventionally, there has been known, for example, an air bag apparatus provided in a steering wheel of a motor vehicle. The air bag apparatus is provided with an air bag body formed in a flat bag shape, a cover covering the air bag body, an inflator injecting gas, and the like. Then, the air bag body is folded to be small in accordance with a certain method at unactivated state so as to be received inside the cover. At a time of detecting an impact of collision by a collision sensor, the air bag body is expanded by injecting the gas from the inflator. The cover is broken due to an expansion pressure of the air bag body and the air bag body is protruded, expanded and deployed to face the passenger, so that the impact of the collision to a passenger is reduced.
The air bag body has been conventionally folded along a straight line at a predetermined position from a state being expanded on a flat plate so as to be formed in a rectangular parallelepiped shape capable of being received in the cover. However, there is a problem that it is hard to mechanically produce the folded air bag body, a lot of labor is required and it is hard to improve the productivity.
In order to improve the above mentioned points, as a folding method suitable for the automation, for example, there has been known a structure shown in International Patent Publication Laid-Open No. WO97/48580. In particular, the air bag body is expanded by using a folding apparatus provided with a folding plate arranged so as to form a coaxial circle shape or a spiral shape in opposite to each other from upper and lower portions of the air bag body. The air bag body is folded by gripping the air bag body by the folding plates, moving or deforming the folding plates toward predetermined hollow space so as to reduce radial distance between each of adjacent folding plates. However, in this structure, there is a problem that the structure of the apparatus becomes complex and it is not easy to reduce the production cost.
Further, with respect to, for example, the air bag body formed in a flat circular shape, there has been proposed a so-called petal fold in which the air bag body is collected toward a center from an outer peripheral portion thereof so as to form a pleat shape. With respect to this method, there have been known structures described in Japanese Patent Publication Laid-Open Nos. 10-129381, 10-217894 and the like.
At present, there is required a structure of an air bag body which can improve the deploying characteristic and reduce the production cost.
The present invention is made by taking the points mentioned above into consideration, and an object of the present invention is to provide an apparatus for folding an air bag body in which the deploying characteristic is improved and the production cost can be reduced.
The first aspect of the invention provides an apparatus for folding an air bag body having a first surface portion having an inlet port from which gas is introduced into the air bag body and a second surface portion opposing to the first surface portion comprising: a table for mounting the air bag body thereon; expanding means for introducing air into the air bag body; a plurality of accumulating means for accumulating the air bag body from a peripheral edge portion toward the inlet port; a guide member for guiding the air bag body along a line between the peripheral edge portion and the inlet port and setting the first surface portion and the second surface portion close to each other; displacing means for pressing a part of the second surface portion protruding away from the inlet port toward the inlet port.
According to the first aspect of the invention, the guide member restricts in a state that the first surface portion and the second surface portion are close to each other along the line toward the inlet port. The air bag body is expanded without being restricted in the other portion than the restricted portion, and the first surface portion and the second surface portion are moved apart from each other. In this state, by pressing and accumulating the portion between the lines, that is, the first surface portion and the second surface portion toward the inlet port, the air bag body is folded in such a manner that the first surface portion and the second surface portion are respectively formed in a wave shape without being engaged with each other. In the air bag body folded in the manner mentioned above, the gas introduced from the inlet port is smoothly supplied to the peripheral edge portion, and it is easy to improve the deploying characteristic. In the air bag body, a height in a front surface of the air bag body is not restricted at a time of accumulating. Accordingly, a large member needed at a time of restricting the height of the front surface is not required, and it is possible to rapidly perform the folding operation by the apparatus having a simple structure, and the production cost can be reduced. The air bag body is arranged in a desired shape by the displacing means. Accordingly, it is possible to easily perform the operation of receiving the folded air bag body in the container. By moving a part of the second surface portion protruding from the accumulated portion, the portion rapidly deploying at a time of introducing the gas can be easily formed. By restricting the expanded air bag body, it is possible to increase the internal pressure of the air bag body and to rapidly move the first surface portion and the second surface portion apart from each other largely.
The second aspect of the invention provides an apparatus for folding an air bag body according to the first aspect of the invention, wherein the guide member comprising an upper guide member and a lower guide member in which the air bag body is put therebetween.
The third aspect of the invention provides an apparatus for folding an air bag body according the first aspect of the invention, further comprising; pushing means for pushing a guided portion of the air bag body along the line against an outer periphery of an accumulated portion of the air bag body.
The fourth aspect of the invention provides an apparatus for folding an air bag body according the third aspect of the invention, wherein the pushing means comprising a rotating mechanism for rotating an air bag body portion adjacent to the inlet port, so that guided portion of the air bag body is received between the accumulating means and the outer periphery of an accumulated portion of the air bag body.
The fifth aspect of the invention provides an apparatus for folding an air bag body according the second aspect of the invention, wherein the upper and lower guide members having substantially equal length along the line.
The sixth aspect of the invention provides an apparatus for folding an air bag body according the second aspect of the invention, wherein the upper guide member is larger in height than the lower guide member.
The seventh aspect of the invention provides an apparatus for folding an air bag body according the first aspect of the invention, wherein the displacing means is descended so as to accumulate an expanding portion located above the air bag body down to form a flat-table-like portion.
The eighth aspect of the invention provides an apparatus for folding an air bag body according the third aspect of the invention, wherein a shape of the air bag body is arranged in a column shape of a regular octagon in plan view having a predetermined height by an operation of the pushing means and displacing means.